D2D (Device-to-Device) communication is a new technology that allows UEs (User Equipments) to directly communicate by multiplexing cell resources, under control of a communication system. The D2D communication can increase spectral efficiency of a cellular communication system and reduce transmission power of the UE. Therefore, to a certain extent, the problem of lacking of spectral resource existed in wireless communication system can be solved.
The R13 version of the 3GPP (3rd Generation Partnership Project) protocol supports point-to-point unicast communication. The point-to-point unicast communication includes relay-related point-to-point unicast communication and non-relay-related point-to-point unicast communication. Direct communication between devices is a kind of short range communication. Before a terminal performs a D2D direct communication, a short range service authentication is required, and only when the short range service authentication has been passed, the direct communication can be carried out.
Further, narrow-band communications, such as eMTC (Enhancement Machine Type Communication), are supported in release-13. However, the exiting short range unicast communication technologies can not be applied to the narrowband terminals.